Dune Erosion Models and Swash Zone Kinematics from Remote Video Observations

摘要

The subaerial beach, composed of sand dunes and the foreshore, provides a natural buffer zone between vulnerable land and the dissipation of storm wave energy due to wave breaking. The natural beauty of this region is attractive to people, and as a result, significant investment has been placed in this relatively unstable strip between land and water. During storms, when water levels and waves exceed the base of the dune and the dunes are vulnerable to erosion, development and ecosystems landward of the dune are at risk. Ideally, predictive models would forecast potential dune erosion, allowing appropriate management response. One class of existing dune erosion models is based on assumed avalanching once foreshore slopes exceed a user defined maximum value, although vertical or even overhanging dunes frequently occur in nature, suggesting that a maximum slope is not a universal parameterization. Another approach relates the volume of eroded sediment to the normal force of impact via an empirical coefficient. However, neither of these approaches addresses the fundamental physics controlling dune erosion. The objective of this dissertation is two-fold. The primary objective is to improve our understanding of the physics driving dune erosion and develop new predictive models. The secondary objective is to develop innovative new methods for studying the dune and foreshore using remotely sensed observations that can provide the data needed to improve our understanding of the processes.